Can you believe that the first quarter of 2015 is almost over? We’ll help you hit the ground running for the second quarter with a load
of helpful network admin how-to articles on using cURL and GNU to test websites and doing CPU performance analysis for Linux. In this issue, you’ll also read about an
interesting hardware bug recently discussed by Google’s Project Zero team.

“Rowhammer” is a known problem with some of the latest DRAM chips, making PCs and laptops vulnerable to bit flips as result of repeated access to adjacent memory rows.
When running on a system with susceptible DRAM modules, with some luck, carefully crafted exploit code might be able to gain full access to physical memory, thus escaping protection mechanisms and gaining control over the system.

The CPU is critical in servers used mainly for applications and databases. It is also usually a source of performance bottlenecks.
However, high CPU utilization does not always mean that the CPU is doing work; it could also be waiting on another subsystem. When you do performance analysis, always look at the system as a whole,
taking care to inspect all subsystems because there may be a cascade effect trickling down that is causing the issue.